hashDerivationModulo: Generalize for multiple fixed ouputs per drv

See documentattion in header and comments in implementation for details.

This is actually done in preparation for floating ca derivations, not
multi-output fixed ca derivations, but the distinction doesn't yet
mattter.

Thanks @cole-h for finding and fixing a bunch of typos.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8de234951..c9a16784e 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -742,7 +742,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 DerivationOutput(StorePath::dummy.clone(), "", ""));
         }
 
-        Hash h = hashDerivationModulo(*state.store, Derivation(drv), true);
+        // Regular, non-CA derivation should always return a single hash and not
+        // hash per output.
+        Hash h = std::get<0>(hashDerivationModulo(*state.store, Derivation(drv), true));
 
         for (auto & i : outputs) {
             auto outPath = state.store->makeOutputPath(i, h, drvName);